From the heart, there are two carotid arteries that split off after leaving the heart and form symmetric arrangements through the neck to feed the left and right sides of the face and brain. One risk factor for stroke in adult patients is the presence of a condition called carotid artery stenosis, which is a blockage or narrowing of the blood vessels that feed the brain. Buildup commonly occurs where the internal and external carotid arteries diverge in the neck, prior to the blood's arrival to the face.
The blockage or narrowing of the blood vessels that feed the brain tends to build up over time and can lead to strokes in two ways. First, an ischemic stroke may occur, wherein plaque in the artery causes a clot to accumulate over time until the clot fully blocks normal blood flow and deprives the brain of oxygenated blood. In contrast, an embolic stroke involves an accumulated clot becoming dislodged and traveling along with the blood further into the brain until it becomes lodged in a smaller vessel and blocks the blood flow.
Preventative screening for asymptomatic stenosis is currently not a recommendation. However, this leaves patients at risk until the first event occurs.